Synthesis of allyl esters with palladium and platinum halide catalysts

ABSTRACT

Preparation of allyl esters of carboxylic acids in improved yields by use of palladium and platinum halides as catalysts in the reaction between allyl halides and salts of carboxylic acids.

' United States Patent Brady 14 1 Oct. 17, 1972 [54] SYNTHESIS OF ALLYLESTERS WITH PALLADIUM AND PLATINUM HALIDE [52] US. CI....,.....260/491,260/4l0.9 N, 260/468 R, 7 260/469, 260/475 N, 260/476 R, 260/485 N [51]Int. Cl ..C07c 67/00 [5 8] Field of Search ..260/491, 476 R, 260/4109 N,485 N, 468 R, 475 N, 469

Donnie G. Brady, Bartlesville, Okla; I

[5 6] References Cited UNITED STATES PATENTS 3,360,548 12/1967 Clerk etal. ..260/491 3,534,087 10/1970 Leftin et al. ..260/491 Kohl] et al...260/49l Primary Examiner-Vivian Garner Attorney-Young and Quigg [57]ABSTRACT Preparation of allyl esters of carboxylic acids in improvedyields by use of palladium and platinum ha- 5 lides as catalysts in thereaction between allyl halides and salts of carboxylic acids.

9 Claims, No Drawings SYNTHESIS OF ALLYL ESTERS WITH PALLADIUM ANDPLATINUM HALIDE CATALYSTS This inventionrelates to a method for thepreparation of esters of carboxylic acids. In one aspect, it relates tocatalysts to improve the reactions of allyl halides with salts'ofcarboxylic and polycarboxylic acids.

Heretofore, it has been recognized that allyl halides react with alkalimetal salts of carboxylic acids at elevated temperatures to form thecorresponding esters. However, yields in general have been low,conversion rates for the esterification or displacement process. havebeen slow thus requiringexcessive residence times in the reactors. Y

While the reaction of allyl halides with 'carboxylic acid salts has beena general method of esterification in the teaching of organic chemistry,yet commercial success has been limited awaiting discovery of methods toincrease yields withswifter surer reactions. One approach has beento usecertain amines and quaternary ammonium halides as catalysts, though withlimited effectiveness. i

Other methods of esterification often involve multiple steps, or userelatively expensive or difficult to handle reagents such asthe acidhalides. Most such processes have shortcomings compared to thesimplicity and ease of using the direct reaction of an allyl halide witha carboxylic acid salt, if such were substantially improved.

I have discovered that the conversion reaction of an alkali metalhydrocarbon carboxylate or polycarboxylate with an ally] monohalide canbe effectively catalyzed by the use of palladium and platinum halidecatalysts.

More particularly, 1 have found my catalyzed esterification reactions toprovide improved yields and improved rates of conversion. These resultsare obtained by the use, as catalysts, of one ormore of the palladiumhalides or platinum halides. p

Therefore, it is the object of my process and catalyst to provide forimproved preparation of esters of hydrocarbon 'carboxylicacidsl It is afurther objectof my invention to provide efficient methods for increasedyields of allyl esters ofhydrocarbon carboxylic acids by the use ofpalladium or platinum halides as catalysts.

The conversion, esterification, or displacement reaction to which Irefer is a reaction between an alkali metal hydrocarboncarboxylate orpolycarboxylate containing up to four carboxylate groups, with an allylmonohalide. The reaction can be represented by:

The number of carboxylate groups may range from one cals can be alkyland with as many as six carbon atoms in the total of R groups.

The catalysts of my invention are the dihalides of palladium orplatinum, specifically PdFg, PdCig, PdBr- Pdlg, PtF PtClg, PtBr and PtlThe dihalides of palladium or platinum can be represented by the formulaPdX or PtX wherein X is F, Cl, Br, or If. These palladium halides can beused singly or as mixtures of two or more.

The equivalent ratio of the alkali metal carboxylate or polycarboxylateto the allyl monohalide is in the range of 0.1:1 to 10:1, and preferablyfrom about 0.5:1

'to 5:1 for most advantageous'operation. From about 0.1 to 100 moles ofcatalyst can be employed per 100 moles-of carboxylate group, thoughpreferably in the range of about 0.5 to 10 moles per 100 moles of thecarboxylate group are employed and result in suitable efficiency andconversion.

Temperatures in the range of from about 0 to about 90 C. are employed inthe esterification reaction with the catalyst of my invention.Temperatures within the range of from about 20 to about 80 C are foundquite effective. Pressures should be sufficient to maintain thereactants and admixtures thereof substantially completely in the liquidphase, a'ndwill usually be in the range of 0.5 to 10 atmospheres.Atmospheric pressure often is a convenience and quite suitable. Reactiontime sufficient to effect the degree of conversion should be employed.Normally, reaction times in the range of from about 1 minute to about 24hours are satisfactory.

Preferably, the conversion should be effected substantially completelyin the absence of water, i.e., under essentially anhydrous conditions tominimize undesirable side reactions. However, minor traces of waternormally found in the reactants do not interfere unduly.

Upon completion of the desired degree of reaction or conversion, theester produced can be recovered in any conventional manner. Any-of theordinary techniques known to the art for separation, such as filtration,stripping, solvent extraction, selective precipitation, and the likecanbe employed as is .necessary orconvenient. v I

gThe esters produced in the process of my invention are valuableproducts for wide commercial use as solvents, or in lubricating oils,and for subsequent polymerization of esters to the valuable polyesters.The esters can be converted to the epoxy compounds and employed withepoxy resin curing agents to form valua- V ble adhesives, coatings, andthe like. Such composieluding fluorine, chlorine, bromine, or iodine. Ris H or v is alkyl, cycloalkyl, aryl, or alkyl substituted aryl havingas many as three alkyl substitutions per aryl group, having in the rangeof from one to about 20 carbon atoms per R group and having a valence ofn. R is hydrogen or alkyl, and up to and including three of the Rraditions also can be employed as plasticizers for synthetic resins andthe like.

My invention is demonstrated by the following examples which should beconsidered as illustrative and not as. limiting. 5

EXAMPLE I To a stirredreactor were added 8.2 g (gram) (0.1 mole) of dry(anhydrous) powdered sodium acetate,

9.2 g (0.12 mole) allyl chloride, 1.8 g (0.01 mole) of I at thattemperature for approximately 3 hours. The adallyl acetate.

EXAMPLE 1i i I Q The. run of Example l was repeated with all conditionsthe same except that no palladium halide or other catalyst was used.Analysis of a portionof the reaction products v.b'y gas liquidchromatography determined that only 20 molepercent of the allyl chloridehad been converted to allyl acetate.

Therefore, comparing the results of Example wherein thereaction employeda palladium chloride as catalyst versus the same. reaction in Example ll'where catalyst, and 50'ml of dimethyl formamide as diluent.

no catalyst was used shows that the reaction according.

to my. invention resulted in' virtually a fourfold in.- crease inproductionof the'allyl ester.

. EXAM LE-1n To a stirred reactor were added 8.2 g (0.10 mole) of drypowdered sodium/acetate; 10.9 g (0.12 mole) freshly distilledl-chloro-2-butene, 50 ml .of dimethyl formamide as diluent, and 1.8 g(0.01 mole) palladium chloride (PdCl as catalyst. The mixture was heatedto I 65C. over art-interval of about 30 minutes and then maintained atthat temperature for 1 additional hour".

Analysis ofthe mixture by gas liquid chromatog raphy indicated that thetheoretical amount, 83 percent, of the l-chloro-2-but ene was. convertedinto. two productsin a 2:3. ratio. The mixture thereupon was heated foran additional 3.5 hours at 65 C. with the composition ratio'oftheproducts remaining the same upon repeat analysis."

The mixture was then cooled inanice bath and fil tered. Thefiltrate waswashed with ml of diethyl ether, and the ether. washings were combinedwith the. filtrate. The combined filtrate and ether washings were washedwith 100-ml ofwater, then an additional 25 ml of diethyl ether was.added, and the ether layer was again washed with 75ml of water. Theether layer was then separated, dried over anhydrous magnesium sulfate,and filtered. The ether was distilled off leaving 1 1.5 g of esterproduct.

Analysis of the ester product by nuclear magnetic resonance showed amixture of about a l:1 mole ratio of 2-butenyl acetate and..l-methylpropenyl acetate. These. palladium andfplatinum catalysts thusshow effectiveness to promote esterification, and also that theyfunction as isomerization catalysts.

' EXAMPLE IV The run as described in Example lll was repeated under thesame reaction conditions with the exception that no catalyst wasemployed. The conversion of l-( Themixture was further treated asdescribed in Example. Ill, and nuclear magnetic resonance analysisdetermined that a single end product had been formed, 2-butenyl acetate.Y

' Comparison of the runs in ExamplesIII and IV shows that after 1.5hours the use of palladium halide catalysts resulted in 100 percentconversionagainst only 30 percent conversion with no catalyst.

EXAMPLE v To a stirred reactor were added 8.2g (0.1 mole). of

dry powdered sodium acetate, .10.9 g (0.l2 mole) of a freshly'distilledmixture comprised of 72 mole percent of 3-chloro-l-butene and 28 molepercent of l-chloro- Z-butene, 1.8 g (0.01 mole) of palladium chlorideas This mixture was heated to C;, and then maintained at thattemperature for approximately] 1 hour. Ex-

amination of the mixture by gas liquid chromatography indicated that 94mole .percent of the 3-chloro-l-butene and 38 mole percent of the1.-chloro-2-butene had i been convertedto 2-.butenyl acetate (65 molepercent) and 1-methyl-2 propenylacetate (35 mole percent). A

totalof 97 mole. percent of the theoretical amount of i the initialcharge of the chlorobutenes had been converted. Heating was continuedfor*1 additional hour without further change in the reaction mixture come.position.

The mixture then was cooled to room temperature an'difiltered. Thefiltrate waswashed with portions of diethyl ether, and the combinedfiltrate and ether washingsywere washed with water, then'dried overanhydrous magnesium sulfate. After filtration and stripping of the etherby distillation,the residue was distilled to isolate an end product of7.4 g (65 mole percent based on. the sodium acetate) of 2-butenylacetate and l-methyl-Z-propenyl acetate mixture.

Examplev V as described. above shows effective preparation of an ally]ester according to the method of EXAMPLE v1-v .The run of Example V.wasrepeated except that, no

'catalyst wase'mployed. After-a reaction interval of 4,5

trace of acetates had been formed.

Thereupon,*to the. reaction mixture a total of 1.0 g (0.006 mole) ofpalladium chloride catalyst was added. After 1 additional hour in thestirred reactor at 65 C., all of the butenylchloride mixturehad beenconverted to a mixture of 2-butenyl acetate mole percent) andl-methyl-Z-propenyl acetate (30mole percent). This shows the immediateeffectiveness of the catalyst, and that the catalyst need not be addedat the initial stages, but can be added subsequently as may be desiredor as may be convenient for commercial production purposes.

Examples given in following paragraphs of some of the reactants that canbe used according tothe process hours, gas liquid chromatographyindicated that only a of my invention should not be considered limitingin a process of myinvention-include:

trisodium 1,3,6 hexanetricarboxylate,

disodium 1,4-cyclohexanedicarboxylate, tripotassiuml,3,6-cyclohexanetricarboxylate, tetrasodium 1,2,7,8octanetetracarboxylate, tetrasodium l,2,4,5-cyclooctanetetracarboxylate,sodium cycloeicosanecarboxylate,

sodium eicosanecarboxylate,

sodium 2-naphthalenecarboxylate,

disodium l,20aeicosanedicarboxylate,

potassium 2,4,-tributylbenzenecarboxylate, tetrapotassium l l 0,1l,20-eicosanetetracarboxylate, tetralithium 1,4,8 12-cycloeicosanetetracarboxylate,

tetrapotassium 2,3,6,7-anthracenetetracarboxylate,

tetrasodium 2,3,8,9-anthracenetetracarboxylate and the like.

Allyl monohalides which can be employed according to the process of myinvention include:

3-chloro-l-propene,

' 3-chl0r0-l-bu tene,

l-bromo-Z-nonene, 3-iodo-l-propene,

3-bromo-l-propene,

3 -fluoro-1 -propene,

2-bromomethyl-1-1-octene,

3-iodo-l-nonene, I

3 -fluoro-2 ,3-diethyll -pentene,

5-chloro-3-ethyl-3-heptene,

5-chloro-4-ethyl-3-heptene,

3-chloromethyl-4-ethyl-3-hexene,

3-bromo-3-propyll -hexe ne,

2-( l-chloropropyl)- l -hexene,

3-chloromethyl-3-octene,

4-iodo-2-methyl-2-octene,

l-fluoro-2-pentene,

2-chloromethyl-l-butene,

3-bromo-1-pentene, and the like. I

It is frequently desirable for the reactions I have described to beeffected in the presence of a gas which is substantially completelynonreactive in the reaction environment. Such gasesas nitrogen, helium,neon, argon, krypton, ethane and other lower paraffin hydrocarbons, andthe like, can be employed.

The conversion or esterification reactions usually are effected in theabsence of added diluents, though where desired for various purposesreaction diluents can be employed in amounts which can comprise as muchas 95 percent by weight of the reaction medium. Examples of materialswhich can be suitably employed as diluents include acetone, methyl ethylketone, methyl isobutyl ketone, tetrahydr'opyran, cyclohexanone,benzene, hexane, toluene, tetrahydrofuran, cyclododecanone,N-methylpyrrolidone, sulfolane, ethanol, propanol, butanol, dioxane anddimethylformamide, and the like, and even mixtures if desired.

Reasonable variations and modifications are possible within the scope ofmy disclosure without departing from the scope and spirit thereof.

That which is claimed is: I I

1. An esterification process which comprises reacting an alkali metalhydrocarbon carboxylate with at least one allyl monohalide, therebyforming the corresponding allyl carboxylate, wherein said process isconducted with reactants substantially in the liquid phase at atemperature of about 0 C. and in the presence of an effective amount ofcatalyst which is at least one palladium halide or platinum halide, ofthe formula PdX or PtX wherein X is F", Cl, Br or I,

wherein said alkali metal carboxylate contains up to four carboxylategroups and the hydrocarbon radical of said carboxylate is alkyl,cycloalkyl, aryl or alkyl substituted aryl contains up to about 20carbon atoms, and said allyl monohalide can be represented by R'C=CRCR'Xwherein each R is hydrogen or alkyl such that the total of Rradicalscontains up to about six carbon atoms, and X is F: Cl-,

Br,o rI e V, 2. The process according to claim 1 wherein said alkalimetal hydrocarbon carboxylate can be represented by R(COM), wherein M islithium, sodium, potassium, rubidium, or cesium, the hydrocarbon radicalof said carboxylate R is alkyl, cycloalkyl, or alkyl substituted phenylaryl having from zero to three alkyl substituents per phenyl group andup to about six carbon atoms in all alkyl substituents per phenylgroup,and n is an integer of 1 to 4.

3. The process according to claim 1 wherein theratio of said carboxylateto said allyl monohalide in said process is about 0.1:1 to about 10:1,and the amount of said catalyst employed in said process is about 0.1 toabout 100 moles per 100 moles of said carboxylate group.

4. The process according to claim 3 wherein said reaction is conductedat a temperature of about 20 C.

to about 80 C., at a pressure of about 0.5 to about 10" conducted in thepresence of a reaction diluent in an amount up to about percent byweight of the total weight of reactants and wherein said reactiondiluent is selected fromfac etone, methyl ethyl ketone, methyl isobutyl;ketone, tetrahydropyran; 'cyclohexanone,

about 12, carbon atoms, tetrahydropyran, cyclododecanone,"N-rnethylpyrolidone, sulfolane, al-

, cohols of fromtwo to aboutseven carbon atoms, dioxane, and mixturesthereof.

7 ."The process of claim 2 whereinsaid allyl monohalide is allylchloride, and said carboxylate is sodium benzene, toluene, xylene,hydrocarbons of from five to ,ils,

2. The process according to claim 1 wherein said alkali metalhydrocarbon carboxylate can be represented by R-(C-O-M)n wherein M islithium, sodium, potassium, rubidium, or cesium, the hydrocarbon radicalof said carboxylate R is alkyl, cycloalkyl, or alkyl substituted phenylhaving from zero to three alkyl substituents per phenyl group and up toabout six carbon atoms in all alkyl substituents per phenyl group, and nis an integer of 1 to
 4. 3. The process according to claim 1 wherein theratio of said carboxylate to said allyl monohalide in said process isabout 0.1:1 to about 10:1, and the amount of said catalyst employed insaid process is about 0.1 to about 100 moles per 100 moles of saidcarboxylate group.
 4. The process according to claim 3 wherein saidreaction is conducted at a temperature of about 20* C. to about 80* C.,at a pressure of about 0.5 to about 10 atmospheres, and during a time ofabout 1 minute to about 24 hours.
 5. The process of claim 3 wherein saidreaction is conducted in the presence of a gas substantially nonreactiveto the reactants, and wherein said gas is selected from nitrogen,helium, neon, argon, krypton, xenon, saturated hydrocarbons of from oneto about eight carbon atoms, and mixtures thereof.
 6. The process ofclaim 3 wherein said reaction is conducted in the presence of a reactiOndiluent in an amount up to about 95 percent by weight of the totalweight of reactants and wherein said reaction diluent is selected fromacetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydropyran,cyclohexanone, benzene, toluene, xylene, hydrocarbons of from five toabout 12 carbon atoms, tetrahydropyran, cyclododecanone,N-methylpyrrolidone, sulfolane, alcohols of from two to about sevencarbon atoms, dioxane, and mixtures thereof.
 7. The process of claim 2wherein said allyl monohalide is allyl chloride, and said carboxylate issodium acetate.
 8. The process of claim 2 wherein said allyl halide is1-chloro-2-butene and said carboxylate is sodium acetate.
 9. The processof claim 2 wherein said allyl chloride is a mixture of 1-chloro-2-buteneand 3-chloro-1-butene and wherein said carboxylate is sodium acetate.